Xj700 Maxim X, weird carb or coil problem

So I’ve had my 85 xj700 Maxim for about 3 months now and I’ve done all of the carb cleaning and checking the diaphragms and whatnot, my issue is that when I’m cruising on the highway I get to about 65-70 MPH, (5000-5500 RPMS), and I try to gun it to give it more gas and the whole bike starts to stutter and I lose all power until I let off the throttle again. I’ve changed plugs changed all fluids put new gas and all of my jets are stock and clean.

 

stock air cleaner and mufflers? what do the plugs look like?

 

It has pods on it from the PO and when I pulled the old plugs 2 of the 4 were a little black from being fouled. Went ahead and replaced all of them with the recomended.

 

Try bumping the choke on a bit the next time you attempt this and see if the results are different. If so, then I would suspect that the fuel levels in the bowls are way too low, or some type of obstruction somewhere (or some other cause) that reduces fuel flowing into the carbs.

 

...or that the carbs weren't rejetted for pods.

 

This is one problem with PODS you have to experiment with the jetting , you will need to go up on jet size 2 to 4 sizes larger if jet is the stock size . Be aware this could cause problems at idle you also would possible need to adjust mixture screw. Pull carbs and see what size of jets are installed , I'm not sure about the 700., my seca 750 120 is main size can't remember the pilot size this is with the stock airbox.

 

Will do, someone else below mentioned getting bigger mains for the pods? You sell the aftermarket “tuning” jets right?

 

Yes we do, but I don't think that is the real source of your issues according to your description of the problem.

What happens if you just roll on the throttle above 5000 rpm's? Does the bike respond normally? What about in lower gears/speeds? Does jumping on the throttle at 5000 rpm's exhibit the same issue?

 

No it sputters and loses power at any increase in throttle once hit hits that mark around 5000-5500. In all the lower gears it’s fine with driving, I’ve never gotten above 5k rpms at lower gears. I’ll try it out and see though.

 

pods+problems=podblems

 

So upon further testing the gear does not matter. Once I get into that rpm range it completely loses power and sputters like mad, could having small jets with pods do that because of fuel starvation?

 

Your OEM diaphragm springs are matched with the pressures corresponding with the flow through the airbox.
Without the correct spring rate, you'll never know if it is incorrect fuel/air ratio or your throttle slides just not cooperating with your wrist.
Easiest solution is an airbox, at least that way you have a proven result at the end.

 

I would have left it alone no telling what the PO was thinking though. Is replacing it as simple as finding an air box and installing?

 

Assuming the PO did not alter the carbs, you'll need the airbox and the rubber fittings and clamps to the carbs.
It's a tight fit to install. Some XJ's require the removal of carbs and tilting the motor forward on the front lower motor mounts to get it in place.
Some have successfully softened the airbox with heat to push it into place.
Some have removed the motor.
I don't believe any of these discussions were specific to the XJ-X so you might be in uncharted waters here.
The airbox is most often destroyed to remove it so they are not as plentiful as some other parts simply removed.
The PO likely believed he was hot-rodding it.
Abbreviating a screaming 10,000 rpm redline in half is not successful hot-rodding.

 

Well dang, if that’s the case it’s almost worth just trying to make it work...maybe rejeting and adjusting springs will help some. I only need 80 MPH lol, I can live with that.

 

I just re-read you original post. You didn't mention it being an X, however I think the 700N frame is essentially the same shape.
Removing the motor may sound daunting but will be less frustrations than carb tuning.
If you do go that route I suggest you buy a Dynojet kit if it is available. If it is not then good luck!
Is your bike air-cooled or liquid?

 

Liquid...I think...sorry I’m still new to these xj’s. It has a radiator up front with coolant so I would assume liquid.

 

Doh, your subject line says X.
You owe it to yourself to get that 5-valver screaming to redline.

 

Update!!! Got on it in 3rd today and was able to get to 6500 RPMS no problem! So it’s only doing it at high speeds? Maybe the stock jets arnt letting enough fuel for the pods at high speeds?